Lenticular contact lense lathe

ABSTRACT

A process for shaping lenticular contact lenses comprising the steps of casting a lense blank with a cast surface shaped to fit over the cornea and of shaping the opposite surface by first shaping the central portion of the optical surface by generating a curvature of the desired radius, and thereafter shaping the peripheral or outer portion of the optical surface by generating a curvature of the other desired radius. The steps are carried out sequentially and automatically on a novel machine. The machine comprises a tool holder mounted on a slidable support pivoted around a first pivot pin. The first pivot pin is supported on a second slidable support pivoted around a second pivot pin. The adjustable swing of the supports determine the multiple curvatures of the optical surface. The pivoted supports are moved sequentially and automatically by interconnecting them with a lost motion connection, whereby one support and the tool pivots freely to generate one curvature until the lost motion is taken up and then the other support and tool pivots to generate the other curvature.

United States Patent Whitham 1 Sept. 17, 1974 [5 LENTICULAR CONTACT LENSE LATHE Primary ExaminerDonald G. Kelly 75 Inventor: Keith A. Whitham, Cheektowaga, f Saffitz N.Y. ABSTRACT [73] Assignee: Warner-Lambert Company, Morris Plains N J A process for shaping lenticular contact lenses comprising the steps of casting a lense blank with a cast [22] Filed: Mar. 5, 1973 surface shaped to fit over the cornea and of shaping [21] Appl. NO: 338,245 the opposite surface by first shaping the central portion of the optical surface by generating a curvature of the desired radius, and thereafter shaping the periphl l Cl 82/12 eral or outer portion of the optical surface by generat- [51] Int. Cl B24b l/OO, B24b 13/00 ing a curvature of the other desired radius. The steps Field of Search 51/284, 33 W, 31-32, are carried out sequentially and automatically on a 5 216 novel machine. The machine comprises a tool holder 12 mounted on a slidable support pivoted around a first pivot pin. The first pivot pin is supported on a second [56] Re e ences C e slidable support pivoted around a second pivot pin. UNITED STATES PATENTS The adjustable swing of the supports determine the 2,237,744 4/1941 Mullen u 51/284 UX multiple curvatures of the optical surface. The pivoted 2,403,668 7/1946 Muddock" 82/11 supports are moved sequentially and automatically by 2,427,020 9/1947 Overzat 2. 82/11 in e nec g t e with a 10st motion connection, 2,633,675 4/1953 Ellis 51/284 X whereby one support and the tool pivots freely to gen- 2,806,327 9/1957 Coburn 51/33 W erate one curvature until the lost motion is taken up 3915-196 1/1962 Campbell 4 51/284 and then the other support and tool pivots to generate 3,1 l7,396 l/l964 Dalton A 51/284 X the other Curvature 3,662,040 5/l972 Urbach 51/284 X 12 Claims, 8 Drawing Figures wmrmsw fl v 3.835.588

sums or 3 CENTRAL CURVE LENTICULAR CONTACT LENSE LATHE This invention relates to the art of shaping lenses, particularly lenticular contact lenses.

An object of the invention is to provide a rapid and economical method for shaping the optical surface of a lense, wherein the optical surface comprises portions of different curvatures.

Another object is to provide a rapid and accurate method for shaping lenticular contact lenses.

A further object is to provide a machine for generating rapidly and accurately the various curvatures of the optical surface of a lense, the machine having a plurality of adjustable pivoted supports for the tool, whereby curvatures of different radii may be sequentially and automatically generated. While U.S. Pat. No. 3,015,196 discloses schematically (FIGS. 17 and 18) a series of pivoted supports for the tool, the operation of generating curvatures thereby is not automatic and sequential.

Another object is to provide a lense shaping machine wherein either the tool holder or lense holder is mounted on a plurality of pivoted adjustable supports and there is provided a lost motion connection between adjacent cooperating supports, whereby each of the supports is automatically actuated around its pivot in a desired sequence to thereby rapidly generate the desired curvatures of the optical surface of the lense in a desired sequence.

Other objects of this invention will become apparent from the following description taken in connection with the accompanying drawing of which:

FIG. 1 is a cross-section of a contact lense blank to be finished as a minus lenticular lense with the finished optical surface indicated by dotted lines;

FIG. 2 is a partial schematic side elevation of the lense shaping machine;

FIG. 3 is a partial cross-section of the machine taken on line 3-3 of FIG. 2;

FIG. 4 is a schematic top view of the machine with the pivoted supports in the zero position;

FIG. 5 is similar to FIG. 4, but showing the pivoted supports in the position at the completion of the center curvature generation;

FIG. 6 is similar to FIG. 4, but showing the positions of the pivoted slides at the end of the peripheral curvature generation; and

FIGS. 7 and 8 illustrate the final curvatures of a finished plus and minus lense, respectively.

FIG. 1 illustrates in section the cast contact lense blank 1 to be turned into a lenticular minus lense. Preferably, the blank is cast as a disc having a curved surface 2 atone of its ends with the required configuration to fit the cornea of the eye. To shape the optical surface 3, the blank is placed in a lathe or grinding machine and machined by proper tools to the desired optical shape. The optical surface of the lense comprises an inner or center surface 3a cut on one radius and an outer peripheral surface 3b cut on a different radius. If a plus lenticular lense is desired, the surface curvatures would also be based on different radii in a manner well known in the art.

The preferred method to shape the lenticular lense is to utilize a novel machine which may have a cutting tool or grinding tool mounted on a first movable slide which is pivotally mounted on a second movable slide, which is further pivotally mounted on a conventional carriage movable on the bed. The slides are adjusted to the several radii of curvature and are then moved sequentially to cut the inner and outer curvatures of the optical surface. Sequential movement of the slides are automatically obtained by the use of stops mounted on the slides, whereby movement of the slide mounting the tool sequentially takes up the lost motion between the stops to move the second slide in sequence.

The preferred machine is a lathe having a base 5 supporting lense blank mounting means 6 and motor 7 to rotate the mounting means. Opposite the lense support means is tool holder 8 supported on a conventional tool support carriage 9 which is slidable in guide-ways formed in a pivoted support 10. Support 10 may be termed as the central swing support since it determines the curvature of the central portion of the lenticular lense. Support 10 pivots around a pivot pin 12. Pin 12 is mounted in a bearing 13 fixed within a bore in support 10 and in a bearing 14 fixed within a bore in a slide member 15 slidable in guidways in a second pivoted support 16. Support 16 may be termed as the peripheral swing support, for it determines the curvature of the outer or peripheral portion of the lenticular lense surface. Support 16 pivots around a pivot pin 17 mounted in a bearing 18 in support 16 and in a bearing 19 in a cross-cut support or carriage 21. Cross-cut support 21 is carried by a carriage 22 slidable in guideways formed in bed 5.

Slides 9 and 15 and carriage 22 are adjustably positioned along their guide-ways by conventional nonshown means, as indicated by arrows 23. The positioning means are well known in the art and may be lead screw means, hydraulic means or similar means connected to the slides and carriage to reciprocate them in their guide-ways.

The outer or peripheral swing support means 15 and 16 carries an adjustable stop 26 which limits the pivotal movement of central swing support 10 in one direction relative to peripheral swing support 16. Stop 26 comprises a threaded member 27 engaging a cooperating threaded opening in a bracket member 28 secured to either slide 15 or its support 16. Similarly, an adjustable stop 29 comprising a threaded member 30 in a bracket 31 secured to cross-cut carriage 21 limits the swing of peripheral swing support 16 relative to either cross-cut carriage 21 or carriage 22 to determine the initial or zero position of support 16. To bias support 16 in its zero position, a flexible means, such as a nylon rope 32, is attached to support 16 and trained over a pulley 33 with a suitable weight 34 secured to its free end to exert a force on support 16 to swing it around its pivot pin 17 against stop 29. Thus, a force is necessary to move pivoted support 16 against the bias of weight 24. In lieu of a weight, a spring arrangement may be used to hold support 16 against its stop 29.

A lost motion connection is provided between central swing support 10 and peripheral swing support 16 whereby, after a free pivotal movement of support 10 around its pivot pin 12, the lost motion is taken up and thereafter continued movement of support 10 forces movement of support 16 around its pivot pin 17. The lost motion comprises a rod member 36 secured to the slide 15 within the space formed by slide 15 and support 10. Rod 36 is secured to slide 15 by a set screw or other convenient securing means. A stop member 37 is slidable along rod 36 and is adjusted along the rod in the desiredposition to be contacted by center swing support 10. A thumb screw 38 holds stop 37 in its adjusted position. Thus, after a predetermined. angular movement of support 10, its slide 9 and the cutting tool holder 8 around pivot pin 12, slide 10, or a means connected to it, engages stop 37, that is, the lost motion connection between supports and 16 has been taken up. Further angular movement of support 10 moves stop 37 and thereby causes support 16 to overcome the bias of weight 34 and to pivot around its pivot pin 17. In view of the engagement of stop 37 and slide 10, the cutting tool will now pivot around pivot 17, and cut the peripheral curvature of the lense, since tool support 8, slide 9 and support 10 make no further angular movement relative to pivot pin 12.

While FIG. 2 shows pivot pins 12 and 17 in almost axial alignment, in actual operation the relative positions of the pivot pins will be adjusted to cut the desired optical curvatures on the lense blank. The position of pivot pin 12 is adjusted relative to the lense by adjustment of slide 15 which supports the pivot. The position of pivot pin 17 is adjusted by sliding carriage 22 along its guide-ways, since it carries cross-cut carriage 21 which supports pivot pin 17.

OPERATION The lense blank 1 is secured to blank holder 6 by an adhesive or other means well known in the art. Slide 9 is adjusted to properly position the tool with respect to the blank. Central swing support 15 is adjusted to move pivot pin 12 to the position to generate the desired central curvature. Carriage 22 is adjusted to position pin 17 and support 16 so that the desired peripheral curvature may be generated. The above steps may be varied as long as the final positions of the parts are in proper working relationships.

FIG. 4 illustrates the relative position of the slides, supports and carriage at the initial or zero position. First the structure of the slide and supports 9 and 10 are actuated either manually by a handle 40 attached hereto, or by some power means. The tool cuts the lense blank as means 8, 9, and 10 rotate around pivot 12. Means 15 and 16 is held from rotating around its pivot 17 by the force exerted by weight 34 on cable 32.

As the cutting tool is swung around pivot 12 by means of central swing plate 10, the central curvature surface is shaped on the lense blank. The central curvature is generated until the central support 10 contacts stop 37, that is, the lost motion between pivoted supports 10 and 16 is taken up. The positions of the several parts at this point of operation is illustrated in FIG. 5. Continued actuation of support 10 forces movement of slide 15 and its support 16 in view of the interconnection of stop means 36 and 37 between the means 10 and 16. The biasing effect of weight 34 on support 16 is overcome and cutter holder 8, slide 9, support 10 and support 16 swing as a unit around pivot 17 to generate the peripheral or outer curvature of the optical surface of blank 1. This position is illustrated in FIG. 6.

Upon the completion of the desired peripheral curvature, the parts are moved to the zero position of FIG.

4 by the weight moving support 16 and slide 15 against its stop 29. The lense blank my then be removed to be trimmed and finished to size at another station. The machine may also be adjusted so that at the final position of the peripheral swing support 16, the blank will be cut and trimmed to completed size at the outer edge of the peripheral surface.

The various gauges and micrometer measuring devices commonly used in the lense shaping art may be attached to the various slides and carriages for precise adjustment of the parts to obtain the accurate positioning of the pivot means and thereby the radii of curvature.

While in the preferred embodiment illustrated the lense blank is rotated in a fixed axis and the tool is manipulated on the pivoted support means, the arrangement may be reversed. that is, the tool may be fixed for cutting or rotated for grinding or cutting in a fixed axis and the lense blank may be mounted, either for rotation or in a fixed position, on a lense mount carried by the pivoted support. ln this arrangement. the lense blank is moved against and relative to the tool.

While the invention has been described and illustrated in detail, it is to be clearly understood that this is intended by way of illustration and example only and it is not to be taken by way of limitation.

What is claimed is:

1. In a method for producing a lense having an optical surface comprising a plurality of curvatures, the steps which comprise:

supporting the lense shaping tool on a first support;

pivoting the support around a first pivot point representing the center of a radis for one of the curvatures;

supporting the first pivot point on a second support which pivots around a second pivot point representing the center of a different radius for another curvature;

biasing the second support with a restraining force to a zero position; and

interconnecting by lost motion means the first support and second support freely around the second pivot until the lost motion is taken up and thereafter sequentially forcibly moving the second support around its pivot against the restraining force.

2. A machine for shaping the optical surface of a lense having a plurality of curvatures comprising:

a lense holding element cooperating with a tool holding element;

a fixed support for one of said elements;

a first pivoted support means for said other element;

a first pivot pin around which said first pivoted support means pivots;

a second pivoted support means carrying said first pivot pin;

a second pivot pin around which said second pivoted support means pivots;

means for interconnecting said first pivoted support means with said second pivoted support means;

yielding means secured to said second pivoted support means to hold said second support means in an initial predetermined position;

means to swing said first support means freely around its pivot to shape the first curvature; and

means responsive to a predetermined angular movement of said first pivoted support means to effect the interconnection of said first and second pivotal support means for joint pivotal movement around the second pivot pin against said yielding means to shape the second curvature.

3. The machine as set forth in claim 2, wherein said lense holding element is secured to the fixed support and the cooperating tool element is mounted on the first pivotal support means.

4. The machine as set forth in claim 3, wherein said interconnecting means comprises lost motion means between the first and second pivotal support means and the predetermined angular movement takes up the free motion of the lost motion means.

5. The machine as set forth in claim 4, wherein the yielding means is a force biasing means and a stop means is provided against which said second pivotal support means is biased.

6. The machine as set forth in claim 5, wherein a second stop means is provided on said second pivotal support means to limit the swing of said first pivotal support means thereby providing a set zero position between said two pivotal support means.

7. The machine as set forth in claim 4, wherein said lost motion means comprises two spatially spaced abutment means which come into abutting relationship upon a predetermined relative movement of said abutment means, one of said abutment means carried by the first pivotal support means and the other abutment means carried by the second pivotal support means.

8. The machine as set forth in claim 7, wherein one of said abutment means is spatially adjustable to vary the distance between said abutment means.

9. The machine as set forth in claim 7, wherein said one of said two spacially spaced abutment means is a surface on the first pivotal support means and wherein said other abutment means comprises an abutment member adjustable along an elongated member which is secured to said second pivotal support means, and means to hold said abutment member in its adjusted position along the elongated member.

10. The machine as set forth in claim 9, wherein said first pivotal support means comprises a first slide carrying the tool and slidable upon a first plate pivoted on the first pivot pin, and wherein said second pivotal support means comprises a second slide carrying said first pivot pin and slidable on a second plate pivoted on the second pivot pin, said second pivot pin being mounted on a slidable carriage movable along the bed of the machine.

11. The machine as set forth in claim 10, wherein the biasing means is secured to said second pivoted plate and a first adjustable stop is provided to be contacted by said second pivoted plate to limit its position under the influence of the biasing means.

12. The machine as set forth in claim 11, wherein a second adjustable stop means is secured to the second slide and positioned to limit the movement of said first plate around its pivot pin and thereby adjust the initial position of the first support means relative to the second support means. 

1. In a method for producing a lense having an optical surface comprising a plurality of curvatures, the steps which comprise: supporting the lense shaping tool on a first support; pivoting the support around a first pivot point representing the center of a radis for one of the curvatures; supporting the first pivot point on a second support which pivots around a second pivot point representing the center of a different radius for another curvature; biasing the second support with a restraining force to a zero position; and interconnecting by lost motion means the first support and second support freely around the second pivot until the lost motion is taken up and thereafter sequentially forcibly moving the second support around its pivot against the restraining force.
 2. A machine for shaping the optical surface of a lense having a plurality of curvatures comprising: a lense holding element cooperating with a tool holding element; a fixed support for one of said elements; a first pivoted support means for said other element; a first pivot pin around which said first pivoted support means pivots; a second pivoted support means carrying said first pivot pin; a second pivot pin around which said second pivoted support means pivots; means for interconnecting said first pivoted support means with said second pivoted support means; yielding means secured to said second pivoted support means to hold said second support means in an initial predetermined position; means to swing said first support means freely around its pivot to shape the first curvature; and means responsive to a predetermined angular movement of said first pivoted support means to effect the interconnection of said first and second pivotal support means for joint pivotal movement around the second pivot pin against said yielding means to shape the second curvature.
 3. The machine as set forth in claim 2, wherein said lense holding element is secured to the fixed support and the cooperating tool element is mounted on the first pivotal support means.
 4. The machine as set forth in claim 3, wherein said interconnecting means comprises lost motion means between the first and second pivotal support means and the predetermined angular movement takes up the free motion of the lost motion means.
 5. The machine as set forth in claim 4, wherein the yielding means is a force biasing means and a stop means is provided against which said second pivotal support means is biased.
 6. The machine as set forth in claim 5, wherein a second stop means is provided on said second pivotal support means to limit the swing of said first pivotal support means thereby providing a set zero position between said two pivotal support means.
 7. The machine as set forth in claim 4, wherein said lost motion means comprises two spatially spaced abutment means which come into abutting relationsHip upon a predetermined relative movement of said abutment means, one of said abutment means carried by the first pivotal support means and the other abutment means carried by the second pivotal support means.
 8. The machine as set forth in claim 7, wherein one of said abutment means is spatially adjustable to vary the distance between said abutment means.
 9. The machine as set forth in claim 7, wherein said one of said two spacially spaced abutment means is a surface on the first pivotal support means and wherein said other abutment means comprises an abutment member adjustable along an elongated member which is secured to said second pivotal support means, and means to hold said abutment member in its adjusted position along the elongated member.
 10. The machine as set forth in claim 9, wherein said first pivotal support means comprises a first slide carrying the tool and slidable upon a first plate pivoted on the first pivot pin, and wherein said second pivotal support means comprises a second slide carrying said first pivot pin and slidable on a second plate pivoted on the second pivot pin, said second pivot pin being mounted on a slidable carriage movable along the bed of the machine.
 11. The machine as set forth in claim 10, wherein the biasing means is secured to said second pivoted plate and a first adjustable stop is provided to be contacted by said second pivoted plate to limit its position under the influence of the biasing means.
 12. The machine as set forth in claim 11, wherein a second adjustable stop means is secured to the second slide and positioned to limit the movement of said first plate around its pivot pin and thereby adjust the initial position of the first support means relative to the second support means. 